YA/Dystopian Girl in the future finds a picture in her attic and it's looks exactly like her but it's was taken before she was born. Spoiler ahead.

[Lakhdeep]

Girl finds a picture in her attic and it looks exactly like her but i was taken 100 years before she was born. Girl gets obsessed and wants to find out what happens to her 'twin' and she finds out that the girl in the picture was murdered. Later she finds out that it was her sister and she was a frozen embryo that got unfrozen 100 years later by a family member/descendant.
So the girl in the picture was actually her twin. If i remember correctly, the girl goes back in time and sees her twin and she sees how her twin died. It ended up being her current boyfriend's grandfather who killed her sister.

I read it in 2014-2016 ish

[bookel]

The magic half / Barrows doesn't seem quite what you are after.

[Kris]

Whispers from the Grave by Leslie Rule?

Google Books preview:
https://books.google.com/books?id=k0S... There are different cover images.

Google search of Goodreads:
site:goodreads.com "young adult" portrait looks like her attic murdered frozen embryo "her twin"